Blood bags are almost universally used for blood collection and storage. They are generally flat-sealed plastic sheets defining a peripheral annular heat seal joining the plastic sheets together into bag walls. Upon filling, the bags of course expand outwardly from their flat-sealed configuration.
When many types of blood bags are placed in a standard centrifuge container, the bottom of the bag is folded within the container. Often, the corners of the blood bags fold around to form closed pockets of fluid which cannot mix with the main body of fluid during centrifugation.
In accordance with this invention, the new contour exhibited by the bag of this invention provides inward folds at predetermined locations when the bag is placed within a centrifuge cup. Furthermore, the inward folds which typically are formed with the bag of this invention during centrifugation are open in nature and do not entrap fluid during the centrifuging operation. Accordingly, better processing of the contents of the bag, for example, for separating plasma from packed cells, may be achieved on a routine basis.